The DVD-Video format for optically readable discs is defined in the DVD Specifications for Read-Only Disc, part 3: Video Specifications (version 1.0, August 1996). Relevant parts therefrom are being disclosed in for instance European Patent Application EP 724 264 and U.S. Pat. No. 5,784,528, respectively document D1 and D2 in the list of referred documents that can be found at the end of this description. Both documents are incorporated by reference herein.
The DVD-Video format as defined in the above mentioned Specifications for READ-Only Disc and disclosed in D1 and D2 was created for storing movies and other video content on read-only DVD media. Some of the features of the DVD-Video format make it less suitable for real-time recording applications.
However, it is desirable to create and record video streams and associated data structures on rewritable media in real time which are should preferably be almost identical to the structures defined in the DVD-Video format. Such rewritable discs should be playback compatible with the majority of the installed base of consumer DVD-Video players. The method according to the invention describes a novel and inventive format for DVD-Video compatible real-time recording of video streams, referred to hereinafter to as Real Time DVD Video Recording or shortly DVD-Video Recording. The format defined is intended for home video recording on an optical medium that is playback compatible with DVD-Video players.
The above-mentioned DVD-Video format demands that data for a VTS be allocated contiguously. This gives all kinds of problems when part of the data is overwritten with new recordings.
When editing is performed or part of a title is overwritten, video object (VOB) and Cell numbering does not follow the rules of DVD-Video anymore. The DVD-Video prescribes incremental numbering of video objects and cells. When recording the disc for the first time that requirement can generally be met. However, when old recordings are (partly) overwritten, or when the user does editing, it may no be possible to maintain the incremental numbering. As the VOB and Cell numbering are incorporated in the real time data in the Navigation Packs (NV-PCK), it takes a lot of time to make the stream correct.
Furthermore, starting within a Cell is not allowed according to the DVD video rules.
A Program Chain that defines a play back sequence of Cells, should comprise a Cell start address and a Cell end address. Splitting or partly overwriting of a Cell leads therefore to new Cells. This has as a consequence adding a new Cell identification number. As the DVD Read Only Video rules requires an incremental Cell and Video Object numbering, all Cells and Video Object should be renumbered. This requires a time consuming update of navigation data within the Cells.